Mysterious “Type Error: non-native scope object” in Firebug

问题

Consider the following HTML:

<!DOCTYPE html>
<html>
<body>
Test page

<!--Start of Zopim Live Chat Script-->
<script type="text/javascript">
window.$zopim||(function(d,s){var z=$zopim=function(c){z._.push(c)},$=z.s=
d.createElement(s),e=d.getElementsByTagName(s)[0];z.set=function(o){z.set.
_.push(o)};z._=[];z.set._=[];$.async=!0;$.setAttribute('charset','utf-8');
$.src='//cdn.zopim.com/?pTR0FiicfJ4aMcmuHI9HfVAB4uzKeFIT';z.t=+new Date;$.
type='text/javascript';e.parentNode.insertBefore($,e)})(document,'script');
</script>
<!--End of Zopim Live Chat Script-->

<script type="text/javascript" async="">
window.addEventListener('load', function() {
    var b = document.getElementsByTagName("body")[0];
    var o = document.createElement("object");
    o.setAttribute("type", "application/x-shockwave-flash");
    var t = b.appendChild(o);
});
</script>
</body>
</html>

jsFiddle here: http://jsfiddle.net/V9jtD/

It contains Zopim widget code, another async script that just adds an "object" tag to DOM. Let the above file be served by a webserver (you can use the jsFiddle: http://fiddle.jshell.net/V9jtD/show/). Open it in MacOSX Firefox 15+ with Firebug activated.

You will see the following error repeated many times:

TypeError: non-native scope object

If the errors donot show up, just refresh the page. And mainly Zopim fails to show up (sometimes appears with incomplete functionality). I could not reproduce this in Firefox/Ubuntu. (It might be reproducible in Firefox/Windows I could not check).

However, in the following cases Zopim loads fine:

Comment out "var t = b.appendChild(o);" (ie. dont append the "object" tag to DOM, or you can just remove second script tag entirely).
Deactivate Firebug.

I essentially want to understand who is causing the error so I can debug it.

Is it Firebug, because deactivating it Zopim works fine? But then removing the second script tag with Firebug enabled does not cause the error.

Is it the second script tag, because removing it Zopim works fine? But then deactivate Firebug and Zopim works fine even with second script tag.

Or is it Zopim itself?

Note that the content in the second script tag is part of function testPlayerVersion() in swfobject.js. I have hit this error when I am trying to add Zopim to a page that already has swfobject.

回答1:

It would probably be easier to work out if the fiddle wasn't loading minified JS from Zopim, but the offending line (roughly beautified) is:

try {
    (0)()
} catch (v) {
    s = v.arguments ?
        'chrome' : v.stack ?
        'firefox' : window.opera && !('stacktrace' in v) ?
        'opera' : 'other'
}

Which looks like a hacky way of detecting the browser. I'm not sure why it's causing Firebug to bail, it might be worth raising an issue with them if it's reproducible.

来源：https://stackoverflow.com/questions/14007062/mysterious-type-error-non-native-scope-object-in-firebug

标签

javascript

macos

firefox

firebug

swfobject